"I accept full responsibility for this error," Konopka said. "As a professional athlete, I am responsible for what I put in my body, and I am to blame for this."

He offered an apology to his teammates, the Sabres organization and his friends and family.

"Unfortunately, I did not take the necessary care to ensure that the product did not contain a prohibited substance," Konopka said. "I want to stress, however, that I did not take this substance for the purpose of enhancing my athletic performance.

Konopka, 33, will be an unrestricted free agent on July 1, but the suspension would take effect if he signs a new contract with a team.

Under terms of the collective-bargaining agreement, a first positive test for performance-enhancing substances results in mandatory 20-game suspension and a mandatory referral to the League's Substance Abuse/Behavioral Health Program for evaluation, education and possible treatment.

For the second positive test, a 60-game suspension is given. The player is suspended permanently for a third positive test, though he is eligible to apply for reinstatement after two years.

New York Islanders defenseman Sean Hill was the only player suspended under the policy in April 2007. He signed a new deal with the Minnesota Wild and served the 20 games with that team.

"I have learned a great deal from this experience, something I hope to be able to share with younger players," Zonopka said. "I will accept this suspension and continue to work hard to prepare for the 2014-15 season."